282 FOUNDERS OF OCEANOGRAPHY 



tide will run through the openings, or they may be arranged 

 in rough wooden crates, the successive layers of tiles being 

 placed alternately longitudinally and transversely, in order 

 to break up the currents of water, delay its passage, and 

 cause eddies, so as to afford every opportunity for those 

 larvae that are ready to come in contact with the hme-coated 

 surface and adhere to it. As many as a couple of hundred 

 young oysters may sometimes be found attached to one 

 tile. The success of a " spat-fall " depends largely upon 

 the weather during the critical days, and upon the collecting 

 tiles being placed in position just at the right time — not 

 too early, as then they may become coated with diatoms 

 and other minute organisms, which render the surface slimy, 

 and so prevent the oyster larvae from adhering. 



At Arcachon the young oysters are allowed to remain 

 on the tiles at least till October or early in winter, when 

 they are about the size of the finger-nail, say J to f inch in 

 diameter. Then the tiles are collected and taken ashore, 

 and the process of " detroquage," or separating the oysters 

 from the tiles, takes place. This is effected very rapidly by 

 a skilled hand, the Httle oyster, with the film of lime to 

 which it is attached, being flicked off the tile rapidly by a 

 square-ended knife. 



Many of the oysters are sold at this stage to the " ele- 

 veurs," who rear and fatten them elsewhere ; but many, on 

 the other hand, are kept for another year or two in the 

 pares at Arcachon. These latter, after removal from the 

 tiles, are placed in flat trays having a floor and a lid of close 

 galvanized wire netting of about J-inch mesh, and these 

 trays are fixed between short posts in the sea on the oyster- 

 pare, so that the tide can run freely through them, 

 supplying the oysters with food and oxygen. Such trays 

 are called " ambulances," or " caisses ostreophiles," and 

 measure about 6 feet by 4 feet, by 6 inches deep. They 

 serve to keep the young oyster during the early period of 

 its life out of the sediment, and they also protect it from 



